The muscular system allows vertebrates to move through skeletal, cardiac, and smooth muscles. Skeletal muscles are made of striated fibers anchored by tendons containing myofibrils and sarcomeres. At rest, the body produces ATP aerobically without fatigue byproducts, while anaerobic activities produce lactic acid. Cardiac muscles are laterally connected and involuntary. Smooth muscles are involuntary and controlled by the autonomic nervous system, unlike skeletal muscles which are controlled through motor neurons that release acetylcholine at neuromuscular junctions to contract motor units.

1. Muscular system Junhyuk.Park